The strategies for handling risk comprise of two main types: negative risks, and positive risks. The goal Of the plan is to minimize threats and maximize opportunities. When dealing with negative risks，there are three main response strategies （），Transfer, Mitigate.

A．Challenge

B．Exploit

C．Avoid

D．Enhance

下列关于果胶酶的叙述正确的是

①具有分泌功能的细胞产生的 ②凡是活细胞都能产生果胶酶 ③果胶酶能将果胶分解成半乳糖醛酸 ④植物、霉菌、酵母菌和细菌均可能产生果胶酶 ⑤果胶酶特指分解果胶的一种酶 ⑥纤维素酶和果胶酶可用于去除植物细胞壁 ⑦组成果胶酶的基本单位是氨基酸或核苷酸[ ]

A．①②⑤

B．②③⑦

C．③④⑥

D．③④⑤